Hall and Klitgaard approach economic history as a sequence of technical and political arrangements to deal with energy. Indeed, they see energy as the single non-substitutable factor of production.

The key issue for them is Energy Return on Energy Invested. How do they calculate EROEI?

a EROI = Energy Output/Energy Input
b EROI = Energy Input/Energy Output
c EROI = Energy Output divided by the price of energy
d EROI = Energy Input divided by the price of energy

Amathematical approximation called the rule of 70 tells us that the number of years that it will take something that is growing to double in size is approximately equal to the number 70 divided by its percentage rate of growth. thus, if mexico's real gdp per person is growing at 7 percent per year, it will take about 10 years(=70/7) to double. apply the rule of 70 to solve the following problem. real gdp per person in mexico in 2005 was about $11,000 per person, while it was about $44,000 per person in the u.s. if real gdp per person in mexico grows at the rate of 5 percent per year: how long will it take mexico's real gdp per person to reach the level that the united states was at in 2005? (hint: how many times would mexico's 2005 real gdp per person have to double to reach the u.s.'s 2005 real gdp per person?

The management of a private investment club has a fund of $250,000 earmarked for investment in stocks. to arrive at an acceptable overall level of risk, the stocks that management is considering have been classified into three categories: high risk (x), medium risk (y), and low risk (z). management estimates that high risk stocks will have a rate of return of 15%/year; medium risk stocks, 10%/year; and low risk stocks, 6%/year. the amount of money invested in low risk stocks is to be twice the sum of the amount invested in stocks of the other two categories. if the investment goal is to have a rate of return of 9% on the total investment, determine how much the club should invest in each type of stock. (assume that all the money available for investment is invested.)

Classify each of the following items as a public good, a private good, a natural monopoly good, or a common resource.(a) measles vaccinations (b) tuna in the pacific ocean (c) airline service in the united states (d) local storm-water system